Need help on the array of matrix.

I have a matrix A in a size of n x 1, where A = [a_11 ; a_21 ; a_31 ; ......... ; a_n1]

I want to separate the row of matrix A in every j rows. Let say j = 3, which mean I will obtain:

[a_11 a_21 a_31] ; [a_41 a_51 a_61] ; ..... ; [a_(n-2)11 a_(n-1)1 a_n1]. The total matrix I will obtain is eaual to n/3.

Then I want to group them as B =

[1 a_11 a_21 a_31 ;

2 a_41 a_51 a_61 ;

3 a_71 a_81 a_91 ;

.................................................. ;

n/3 a_(n-2)1 a_(n-1)1 a_n1]

Answer 1

[Stephen23]

B = reshape(A,3,[]).'

[Yuri]

Thank you!